Project description:This sample was prepared with a modified version of the Tn4001 transposon commonly used in Mycoplasmas. This transposon is described to work more efficiently in Mycoplasma agalactiae and, by extension, in other Mycoplasma species. This sample was prepared transforming this bacteria with a newly designed transposon named pMTnGm-SynMyco to test its efficiency by Transposon Sequencing tracked by deep sequencing.
Project description:Mycoplasmas are important model organisms for Systems and Synthetic Biology, and are pathogenic to a wide variety of species. Despite their relevance, many of the tools established for genome editing in other microorganisms are not available for Mycoplasmas. The Tn4001 transposon is the reference tool to work with these bacteria, but the transformation efficiencies (TEs) reported for the different species vary substantially. Here, we explore the mechanisms underlying these differences in four Mycoplasma species, Mycoplasma agalactiae, Mycoplasma feriruminatoris, Mycoplasma gallisepticum and Mycoplasma pneumoniae, selected for being representative members of each cluster of the Mycoplasma genus. We found that regulatory regions (RRs) driving the expression of the transposase and the antibiotic resistance marker have a major impact on the TEs. We then designed a synthetic RR termed SynMyco RR to control the expression of the key transposon vector elements. Using this synthetic RR, we were able to increase the TE for M. gallisepticum, M. feriruminatoris and M. agalactiae by 30-, 980- and 1036-fold, respectively. Finally, to illustrate the potential of this new transposon, we performed the first essentiality study in M. agalactiae, basing our study on more than 199,000 genome insertions.
Project description:Here, we report a CRISPR/Cas12k-transposon-assisted genome engineering (CTAGE) method that allows for high-throughput site-specific mutagenesis in microbial genomes. Exploiting the powerful CTAGE technique, we construct a site-specific transposon mutant library focusing on all the possible transcription factors (TFs) in Pseudomonas aeruginosa, enabling comprehensive identification of essential genes and new factors for antibiotic resistance.
Project description:DNA transposon-based gene delivery vectors represent a promising new branch of randomly integrating vector development for gene therapy. For the side-by-side evaluation of the piggyBac and Sleeping Beauty systems - the only DNA transposons currently employed in clinical trials - during therapeutic intervention, we treated the mouse model of Tyrosinemia type I. with liver-targeted gene delivery using both transposon vectors. For genome-wide mapping of transposon insertion sites we developed a new Next Generation Sequencing procedure called Streptavidin-Based Enrichment Sequencing, which allowed us to identify approximately 1 million integration sites for both systems. We revealed that a high proportion of piggyBac integrations are clustered in hot regions and found that they are frequently recurring at the same genomic positions among treated animals, indicating that the genome-wide distribution of Sleeping Beauty-generated integrations is closer to random. We also revealed that the piggyBac transposase protein exhibits prolonged activity, which predicts the risk of oncogenesis by generating chromosomal double-strand breaks. Safety concerns associated with prolonged transpositional activity draw attention to the importance of squeezing the active state of the transposase enzymes into a narrower time window.
Project description:Analysis of the episomal backbone's influence on gene expression. The first hypothesis tested in the present study is that the episomal EBNA vectors, which rely on the EBNA-1 oncoprotein for episomal maintenance, have a greater influence on the cells' expression profiles than S/MAR vectors. The second hypothesis tested was that when bacterial sequences are removed from the episomal vector backbone, the gene disturbance is minimal.
Project description:Adoptive cellular therapy using genetically engineered immune cells holds tremendous promise for the treatment of advanced cancers. While the number of available receptors targeting tumor specific antigens continues to grow, the current reliance on viral vectors for clinical production of engineered immune cells remains a substantial bottleneck limiting translation of promising new therapies. Here, we describe an optimized methodology for efficient CRISPR-Cas9 based, non-viral engineering of primary human T cells that overcomes key limitations of previous approaches. By synergizing temporal optimization of reagent delivery, reagent composition, and integration mechanism, we achieve targeted integration of large DNA cargo at efficiencies nearing those of viral vector platforms with minimal toxicity. CAR-T cells generated using our approach are highly functional and elicit potent anti-tumor cytotoxicity in vitro and in vivo. Importantly, our method is readily adaptable to current Good Manufacturing Practices (cGMP) and clinical scale-up, offering a near-term alternative to the use of viral vectors for production of genetically engineered T cells for cancer immunotherapy.
Project description:PIWI proteins and their guiding Piwi-interacting small RNAs (piRNAs) are crucial for fertility and transposon defense in the animal germline. In most species, the majority of piRNAs are produced from distinct large genomic loci, called piRNA clusters. It is assumed that germline-expressed piRNA clusters, particularly in Drosophila, act as master regulators to control the activity of transposons dispersed across the genome. Here, using synteny analysis, we show that large germline clusters are evolutionarily labile, arise at loci characterized by recurrent chromosomal rearrangements, and are mostly species-specific across the Drosophila genus. By engineering chromosomal deletions in D. melanogaster, we demonstrate that the three largest germline clusters, which the generation of >40% of all transposon-targeting piRNAs depend on, are neither required for fertility nor for the regulation of transposon activity in trans. We provide further evidence that dispersed active elements, rather than the regulatory action of large Drosophila germline clusters in trans, may be central for transposon defense.